Homojunction-structured ZnO light-emitting diodes fabricated by dressed-photon assisted annealing

Abstract

We formed a p-n homojunction by implanting nitrogen ions, serving as a p-type dopant, into an n-type ZnO crystal. A forward bias current was injected into the crystal while irradiating it with light, bringing about Joule heating which annealed the crystal and changed the spatial distribution of the N-dopant concentration. This activated the N-dopant, causing its concentration distribution to be modified in a self-organized manner so as to be suitable for generating dressed photons. A light-emitting diode fabricated by this dressed-photon assisted annealing method showed electroluminescence at room temperature. In a device fabricated by annealing under irradiation with 407 nmwavelength light, at a forward bias current of 20 mA, the peak wavelength of the electroluminescence was 436 nm, the optical output power was 6.2 μW, and the external quantum efficiency was 1.1 × 10 -4. The emission spectral profile depended on transitions from intermediate phonon states. © The Author(s) 2012.